In an air-conditioning apparatus such as a multi air-conditioning apparatus for a building or the like, a refrigerant is circulated between an outdoor unit, which is a heat source unit arranged outside the building, and an indoor unit arranged inside the room of the building, for example. Then, the refrigerant dissipates or absorbs heat, and cooling or heating of the air conditioning space is performed by the heated or cooled air. As for the refrigerant, HFC (hydrofluorocarbon) refrigerant, for example, is often used. Also, use of a natural refrigerant such as carbon dioxide (CO2) or the like has been proposed.
Also, in an air-conditioning apparatus called a chiller, cooling energy or heating energy is generated by the heat source unit arranged outside the building. Then, water, an anti-freezing solution or the like is heated or cooled by a heat exchanger arranged in the outdoor unit and conveyed to a fan coil unit, a panel heater or the like, which is an indoor unit, so as to perform cooling or heating (See Patent Literature 1, for example).
Also, an apparatus called an exhaust heat recovery chiller is known in which four water pipelines are connected between the heat source unit and the indoor unit, cooled or heated water or the like is supplied simultaneously, and cooling or heating can be freely selected in the indoor unit (See Patent Literature 2, for example).
Also, an apparatus is known that is configured such that heat exchangers for primary refrigerant and secondary refrigerant are arranged in the vicinity of each indoor unit and the secondary refrigerant is conveyed to the indoor unit (See Patent Literature 3, for example).
Also, an apparatus is known which is configured such that branch units having an outdoor unit and a heat exchanger are connected by two pipelines so that the secondary refrigerant is conveyed to the indoor unit (See Patent Literature 4, for example).